Recovery of nutrients from wastewater

water pollution

Water pollution continues to be one of the serious concerns facing the country. The ensuing scenario of eutrophication and harmful algal blooms has exacerbated the menace. This demands wholescale water management techniques to segregate the pollutants, retrieve useful nutrients, and treat the water effectively for sustainable use. Dr Karthik Rajendran and his PhD scholar, Mr Sarath Chandra, from the Department of Environment Science have published a paper discussing various nutrient recovery methods and their consequential outcomes. The research was done in collaboration with Dr Deepak Kumar from SUNY College of Environmental Science and Forestry, Syracuse, NY and Dr Richen Lin from Southeast University, Nanjing, China.

The article titled, “Nutrient recovery from wastewater in India: A perspective from mass and energy balance for a sustainable circular economy” was published in Bioresource Technology Reports (Q1 Journal), having an Impact Factor of 4.41. Their research investigates the possibilities of recovering Nitrogen (N) and Phosphorous (P) from wastewater in terms of technology, energy, and economic point of view. Excessive presence of Nitrogen and Phosphorous can result in eutrophication and algal blooming. These nutrients also pose a harmful threat to infrastructure. Nutrient recovery can mitigate these challenges and improve the quality of water.

Phosphorus is one of the limited resources available on earth and a key ingredient in fertilizer production. The recovery process also helps in transforming wastewater into resource pools that can efficiently churn out valuables that hold the key to a sustainable future. This will help reduce the imports of fertilizers and bring down the emissions to half in producing fertilizers. Their findings will also pave the way for making necessary policies to reduce water pollution and recover nutrients. As two-thirds of wastewater remains uncollected, they claim that effective treatment and water management practices can save around 800 crores per annum. Their future research plan also includes the experimental analysis of the nutrient recovery system.

Abstract of the Research

Wastewater (WW) is a potential source to recover N, and P, whereas, in India, it is scarcely explored. In this work, four different nutrient recovery methods were compared from a mass- and energy-balance perspective to understand the overall process flow. From 1000-m3 WW, chemical precipitation yielded 33.8 kg struvite, while micro-algae resulted in 299.1 kg (dry powder). Energy consumption was lowest for the fuel cells at 216.2 kWh/1000 m3, while microalgae used the highest energy at 943.3 kWh/1000 m3. Nonetheless, the cost-saving analysis showed that microalgae (78.6$/1000 m3) as a nutrient recovery choice, had higher savings than any other methods compared. For a country like India, where two-thirds of urban wastewater is untreated, wastewater-biorefinery options such as nutrient recovery hold the key to a sustainable circular economy.

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